Modern computer and communication networks provide access to an ever increasing variety and number of online services (e.g., databases, services, commerce, etc.) to users and user devices. Many of these online services deal with potentially sensitive or private information (e.g., personal information, financial information, etc.). As a result, services providers have traditionally employed various security measures in order to protect users' information as well as their network resources, databases, and the like, and to provide a certain quality of service and trust over their networks. Traditionally, authentication mechanisms include requiring users to have/create user accounts and passwords, device authentication through digital certificates, and/or other identification means. Once authenticated, users or their devices are authorized to access information, networks, databases, and other resources. Further, some services authorize users with CAPTCHAs to verify that the users are human and not automated computer programs or robots (bots). However, network security threats are becoming more sophisticated and can potentially overcome these security measures. As a result, service providers and device manufacturers face significant technical challenges to developing security measures to protect user information and network resources.